Description

When a user's timezone is not UTC, creating an All Day event in a specific way will make the duration over 2 days.

Steps to Reproduce
1. Go to User's My Account -> Display Settings, and change the Timezone to any setting other than UTC
2. Go back to any page and add the Calendar portlet
3. Click in the gray box (All Day row) to initiate the creation of All Day events
4. Click Edit
5. Click Save
You'll see that the event now spans 2 days instead of one.

Note: Instead of Step 3, you can also use the "Add Event" button to reproduce the same behavior by checking the "All Day" checkbox.